Depending on the operating system you are using:
1. Do a virus scan/torjan scan/spy-ware/ad-ware scan to see if those are causing your problems at all.
2.
http://download.com.com/3000-2094-15...ml?tag=lst-0-1
Get that program. Then go into the control panel after installing the program and click on the startup icon. Check to see what programs occur when you startup your comptuer( you can enable/disable which programs you want too start)
3. Do a windows update
4.
www.microsoft.com
search for a possible shutdown patch to try and fix your problem